This study will investigate the sensitivity and specificity of FLT-PET/CT in primary breast cancer detection and in the use of FLT-PET in monitoring how well a breast tumor respond to treatment. We will compare this technique with other imaging modalities as well as with tissue collection (during a biopsy). We will recruit women with a newly diagnosed invasive breast cancer, who are able to tolerate undergoing a PET/CT (possibly two scans) scan,